How to Downgrade Synology DSM

After upgrading my DS112j from DSM 5.2 to 6.1 and spending a weekend with random lockups and blue blinking light I finally managed to downgrade back to 5.2 (and then 6.0.2 where I stay for now). Reading the Synology forum I learned that I wasn’t the only one who had bad experience with DSM 6.1. The downgrade tutorials that worked with DSM 4 and 5 no longer work with 6.1 so it took a lot of googling and some trial and error and voila! Finally figure it out. I though I would share it here to save someone some time.

Here is how I did it:

• after booting do the “double reset” (press reset 4 seconds until it beeps, then press again right away until you hear 3 beeps).
• the system will reboot. Wait for the reboot to finish until you hear a beep.
• do a search in Synology Assistant (SA). You should see your NAS there.
• create a “fake” .pat file and save it as “DSM_DS211j_15047.pat”. (By “fake” I mean create any text file in Notepad and put few characters in it).
• select the fake .pat file with SA and start the “update”
• the update will fail at about 4%. That’s what we want. It will open up a Telnet port 23
• now the SA Status will say Migratable
• open Putty. Login as “root”. Password for the root is “101-0101”
• now we need to edit the “VERSION” file:

type in “vi /etc.defaults/VERSION” and you will see:

majorversion="6"
minorversion="1"
productversion="6.1"
buildphase="GM"
buildnumber="15047"
smallfixnumber="0"
builddate="2017/02/14"
buildtime="04:30:28"
unique="synology_88f6281_211j"
extractsize=586616 

press “i” to enter the edit mode and change the text to this:

majorversion="5"
minorversion="2"
productversion="5.2.3"
buildphase="hotfix"
buildnumber="5644"
smallfixnumber="0"
builddate="2016/04/26"
buildtime="04:30:28"
unique="synology_88f6281_211j"  **make sure to replace "211j" with whatever your model is**
extractsize=586616

when done editing press ESC, then press “:wq” in sequence to save the changes

• search in SA will now show version 5.2.3-5644
• download 5644 .pat file from Synology site and install it with SA. Wait until it reboots.
• SA might ask you to finish the configuration. Ignore it and close it.
• login to DSM vai web as admin. Password is empty. Finish the setup. Make sure to disable automatic updates or you will end up with 6.1 again.

Now you can upgrade to whatever version you want. Just stay away from DSM 6.1 😉

You will probably lose you configuration even if you saved it since V6 is not compatible with V5 (can’t confirm though). I believe you could go directly from 6.1 to 6.0.2 but you would need to adjust the VERSION info accordingly. And of course – do it at your own risk.